This attractive shrub or small tree grows to about about 5m tall and has a short trunk covered with fissured, corky bark.
From mid summer to early winter Banksia plagiocarpa produces cylindrical flower spikes of an unusual colour for banksia, being mauve tipped with gunmetal grey. The new growth is rusty red and covered in red velvety fur.
As with all banksia they produce much nectar and attract birds and small mammals. This species is tolerant of humid conditions.